Fuse for rotating projectiles



June 7, 1932. E. w. BRANDT 1,851,521

FUSE FOR ROTATING PROJECTILES Filed May 22. 1951 2 Sheets-Sheet l Y n ilJune 7, 1932. E. w. BRANDT FUSE FOR ROTATING PROJECTILES 2 Sheets-Sheet2 Filed May 22. 1951 Patented .lune 7, 1232 EDGAR WILLIAM BRANDT, FPARIS, FRANCE FUSE FOR BOTATING PROJECTILES Application led May 22,1931, Serial No. 539,382, and in France J'une 4, 1980.

The present invention has for an object a fuse intended to be mounted onrotating projectiles, and is capable of being utilized in anti-aircraftfire.

For such employment it is desirable that the fuse should be soconstructed that:

1. It avoids any risk of accidental percussion during the'course oftransport and handling.

2. It must not operate prematurely in case of encountering an unexpectedobstacle in the gun barrel or upon leaving the mouth of the barrel.

3. It must subsequently be sensitized and capable of being actuated byan obstacle of very low mass (air-ship fabric).

4. It must be automatically re-locked dur-i ing the latter part of itstrajectory, to avoid any danger of explosion `when the projectile fallsback to the ground without having encountered its objective.

In order to respond to these conditions, employmentlias been made of therotation at variable velocity to which the projectile is subjectedduring its trajectory when it is fired from a rifled barrel.

This velocity decreases little by little due to the effect of airresistance, and particularly in the case of projectiles of smalldiameter, the velocity of rotation may drop to a third or a quarter ofits initial value. This peculiaritylias been applied, according to thepresent invention, in the followingr manner:

The fuse'comprises a safety device which opposes percussion duringltransport and manipulation. This device is moved out of the way at theend of a regulatable period of time after the firing of the shot, underthe effect of centrifugal force. and comes into play` again, to preventpercussion, when the velocit)Y of rotation of the projectile falls belowa certain value.

T he safety device is formed b v locking elements which are constantlyheld in active position by one or more elastic-elements Whose action canonly be overcome temporarily by entrifugal force for a certain portionof the trajectory of the projectile.

'lhe invention has, further, a certain number of peculiar arrangementsintended especially to maintain the firing pin in forward position inopposition tothe air resistance, to assure a uniform peripheraldistribution of the locking elements during flight, to maintain thepyrotechnic elements firmly even 55, under the very high accelerationsduring propulsion, and, in a general manner, to attain a satisfactoryand definite functioning.

Other advantages and peculiarities of the invention will appear from thefollowing deec scription. K

On the accompanying drawings, solely by way of example:

Figure 1 is an axial section of a fuse according to the invention.

Figures 2 and-3 are diagrams of details. Figure 4 is an axial section ofa modified form of construction.

Figure is a similar view of one particular construction of the firingpin.

Figure 6 is a transverse section on line 6 6 of Figure l, the ballsbeing represented in dotted lines.

l Figures 7 to 11, inclusive, are axial sections of modified forms ofconstruction of the fuse.

Figure 12 is a transverse section on line 12-12 of Figure 11.

Figures 13 and 14 are axial sections of other forms of construction.

Figure 15 is a transverse section on line 80 15--15 of Figure 14.

Figures 16 and 17 are axial sections of further modified forms ofconstruction.

According to the form of .construction shown in Figure 1, the fusecomprises a firing pin 1 mounted to slide longitudinally in a strongnose piece 2, which is fastened to the body 3 of the projectile byintermediate pieces 4 and 5. This fastening is preferably produced byaid of the threaded portions 6 which 90 cooperate with the threadedportions 7 the threading being of suitable pitch and direction so thatthe effect of the rotation will tend to hold the pieces in position. Thelocking elements formed for example by the balls 8, are disposed in acavity 9 around the firing pin l. These balls are actuated in suchmanner as to prevent the operation of the firing pin 1 when the fuse isnot rotating.

For this purpose (Figure 1) they .are l0( centered in thelocking'position by a ring 10 held by the yspring 11 which presses themonto a special seat 12 provided in the cavity 9.

. The form of this seat is chosen in such manner as to permit regulationof'the safety at themouth of the gun and to assure efficient locking atthe end of the trajectory, as will be explained hereinafter. lThe saidseat may comprise a groove 12a (Figure 2) having the form of the balls,or also a surface 12 (Figure 3) having a greater inclination withrespect to the lower wall of the cavity 9, which as a wholemay'advantageously have a diameter which increases from the rea;` towardthe front (Figure 1).

y.The firing pin comprises a shoulder 13 of appropriate form forcooperating with the balls 8 to prevent any premature percussion. Thisshoulderl may have the same shape as the lower seat for the balls, or beform-ed differently, the assembly being preferably of suchtype as toimprison the balls 8 for more than a hemisphere in the locking position,as represented in Figures 2 and 3 where the normals to the points ofexternal contact form between themselves angles, a, a', greater than 180degrees.

The head of the iiring pin may comprise a proj eeting portion 14 whichhas the external shape of'the'projectile (Figure 1) or may remain ratherHat (Figure 4'). Its stem 1 '(Figure 5) has preferably, at one or morepoints, a section of lesser resistance than at the region of thesupporting shoulder 13. This may be attained, for example, by aid ofperforations (Figure 5), or again bygiving vthe firing pin, for acertain distance` a reduced cross section etc.

An abutment 17 (Figure 1), formed by Hanging or otherwise forming thepiece,

j holds the firing pin 1 in its cavity, in opposition to the action ofthe spring 1I. which tends to move it toward the front. Other means vmayfurther be employed for holding the firmg pin in the position of Figure1 during Hight. Thus, this may be attained by utilizing the reaction ofthe air` which may be caused to operate in known manner by count- 'erpressure upon the rear of the firing pin.

The channel 18 provided in the head of the firing pin and opening to theexterior at the point of maximum pressure (Figure 5) permits theestablishment of this pressure atfthe interior of the fuse. A certaintravel is provided between the point 19 of the'ring pin and the primer20 which is held fast and supported by a ring or sleeve 21 solidlyseated in the piece 5 by threading or otherwise (Figure 1).

With a Vvievi7 tol increasing the safety, the

' point of the firing pin and the sealing sheet 23 of the primer 20 maybe formed in such manner as to constitute a soft point-hard plate ofknown type such as described in French Patent 1926.

Below the primer 20 is the detonator 24 whose bottom 25 may be fiat, butwhich has preferably an appropriateform, hemispherical for example, asat 25a (Figure 4), as'- suring the maximum of resistance of deformationunder the effect of the forces to which the projectile is subjected,especially at lirmg. .l

Plastic washersl26 and 27, or Similar backings, maybe utilized tocontribute inv assuring the immobility of the detonator and of theprimer after they have been put in position. At firing, the positiveacceleration forces the balls 8 solidly against their seat in thelocking position under the effect of their own inertia as well as thatof the ring pin 1. of the ring or sleeve 10 and of the spring 11. At thesame time the assembly begins to rotate, carried along by the rotationof the projectile. The angle of inclination ofthe lower surface of thecavity 9 Figure 1) is "selected in such manner that the effect ofcentrifugal force, which tends to separate the balls 8 from the firingpin 1, remains less than the effect of the' forces of #622391, datedFebrry 9,

aoy

inertia. tending'to maintain the balls in the j' locking position duringthe entireduration of the positive acceleration.

When this'acceleration has ceased, the balls 8 separate from the firingpin, under the effect of the centrifugal force, pushing the ring orsleeve 10 forward, against the action of spring 11. However, thisunlocking movement requires a certain time. In effect, the balls,supported against the walls of the cavity 9, are only carried along bythe projeetlle progressively, and the unlocking can only take place whenthe balls have apquiredl a sufficient energy for raising the ring sothat they may leave their seat and eventually free the outlet from thegroove 12a (Figure 2).

'This time of retardation for the unlocking of the firing pin permitsobtaining security at the mouth i. e. it avoids any premature percussionwithin the barrel and at passing from the mouth therefrom, when theprojectile has not traversed a certain distance co rresponding to thetime of retardation in question.

Furthermore, the duration or the distance of this safety may beregulated at will by varying the diameter of the portion of the cavityportion upon which the balls 8 roll. Tlius, by providing in the bottomwall of the cavity 9 a conical portion whose apex angle is less thanthat of the upper portion, the energy acquired at the beginning of themovement of the balls (for a given velocity) is diminished and theunlocking is thus retarded.

Thus the safety distance may also be regulated by varying theco-efficient of friction of the balls 8 on the walls of the cavity 9which may for its purpose, be formed, covered, or

coated with various materials, for example, plastic materials, if it isdesired to obtain a more rapid engagement of the balls for movement withthe projectile, since the balls thus will tend to become encrusted inthe- Ifiring is directed, its -velocity of rotationV gradually decreasesunder the .effect of the air resistance and the moment arises at whichthe energy, due to the rotation of the balls 8, will be insuiicienttoovercome the pressure of the spring 11, which then automatically returnsthe ring or sleeve and the balls 8 into the locking position. From thismoment percussion is no longer possible, and, at' the end of thetrajectory, the projectile drops into the ground without exploding.

It may be remarked that the forms given to the supporting shoulder 13 ofthe firing pin and to the seat 12 or 12a for the balls 8 cooperate tofirmly imprison the balls for more than Aa hemisphere (Figures 2 and 3)and thus oppose any effect of inertia capable of forcing the ballsforward during the slowing down of the projectile in the ground.

This disposition is particularly interesting for cases where theprojectile falls, at the end of its trajectory, onto a terrain ofextremely low consistency, such as heath soil, a sandy shore, marshyground. etc.

Itwill be understood that the angle of inclination of the walls of thecavity 9` the mass and the travel of the balls 8. as well as the forceof the spring 11, are regulated in order that the unlocking andrelocking may take place at. suitable points of the trajectory, accountb eing taken of the velocity of rotation of the projectile.

Radial pathways for rolling may. if desired, be provided on the. lowersurface of the ring or sleeve 10 (Figure 6), or inthe cavity .9, toassure a uniform peripheral distribution of the balls 8 on these walls.

In case ofan accidental fall from a great 2 height or an extremelyviolent shock, the liring pin 1 (Figure 5) will be deformed or crushedin adjacent the holes 16 without the pin 19 causing the firing oftheprimer 20.

Figure 7 shows that a ring or sleeve 32 may be utilized which is fiaredout toward the bottom and whose internal walls play a part analogous tothat of the conical walls of the cavity 9 of Figure 1.

In the construction of Figures 4 and 8. the assembly of the fuse isenclosed in a body *5 33 formed of a single piece, threaded at 34 intothe projectile. The point 19 of the tiring pin 1 is disposed in suchmanner as to directly actuate the detonator 24 without the interpositionof a primer. This detonator is preferably embedded in the charge asrepresented, t-o assure thc ignition under the best possible conditions.l't may loe formed by materials under different compressions or ofdifferent nature, chosen in such manner as to attain at thc same timethe sensitivity and the safety of functioning,r which are desired. Thus.for example, the material (fulminate) placed in the upper portion of thedetonator may be less rammed or of more sensitive composition than thematerial placed beneath. l

The shoulder 37 (Figure 4) constantly maintains the projectile chargenear the detonator 24, even if under the action of the initialacceleration, a certain packing or ramming is produced in the cavity 38.

In the construction of Figure 8, the ring or sleeve 1,0 and the spring11 of Figures 1 to 5, inclusivfef, are replaced by a rigid washer 39 andan elastic or plastic Washer 43 (of cork, for lexample) which plays thesame parts as these two elements.

The elements for locking ,the firing pin may also be formed by balls 8subjected to the action of springs 40 disposed in radial cavities 41 andcoming into engagement. with the firing pin 1 (Figurel 9), or again byone or more Wedge pie es'f42 which may be inserted between the'iriiigpin and the primer 20 .(Figure 10) or by segments 45 (Figures 11 and12). 45a. (Figure 13) which are extensible under the action ofcentrifugal force or in opposition to the action of a spring or otherelastic element (Figure 12).

In another form of construction (Figures 14 and 15) the firing pincomprises elements 45, connected to or formed integral with it, whichyield to the impact, when the balls have gained the unlocking position,to permit the. tiring pin to come into engagement with the primer 20.Thus a certain travel between the pin 19 and the primer 20 is gained atthe moment of the percussion, which is essential for a correct function.

Figure 16 shows another construction according to which the ifiring pin1 is seated, at rest, on the head of the fuse, 51. and comprises ahollow extension 52 enclosing the primer Under the effect of rotation,the balls 8 bring the firing pin into the position 1a (Figure 17) inopposition to the spring 11 and percussion takes place at impact by thecrushing of the portion 52 and the projection of the primer 20 onto thefiring pin which has been stopped by the objective. A

Figure 17 shows a construction analogous thereto with the soledifference that the firing pin 1n. is fastened on its extension 57 by apin 58 which is broken at impact.

Figures l, 16 and 17 show that the fuse may have a form perfectly'corresponding to or capable of construction 1n a very smal] space,

is particularly suited for projectile of small caliber.

rlhe principle of its operation also renders it especially valuableforthat type of projectiles in which the velocity of rotation, all otherthings being equal, decreases in large proportion during the course ofthe trajectory under the effect of air resistance".

lt will be understood that its application to projectiles of largercaliber is only a matter of regulation.

Naturally, 'the illustrated and described modes of construction haveonly been chosen by way of example; numerous modifications of detail maybe employed without departing from the scope of the invention.

Having thus described the invention, what ll claim as new and desire tosecure by Letters Patent, is

l. A fuse for rotative ing a body, onater, firing cated between saidmember and anvinternal surface of said body and operated bycenprojectiles comprisa contact firing member, a deta deformable ringsurrounding said trifugal force to move radially away from said firingmember, whereby they pass from a locking position into a position inwhich they will cause and permit deformation of said deformable memberupon impact and permit said firing'member to engage "said detonator.

2. A fuse for rotative projectiles comprising a body of one piecehavingf cavities at the front and rear ends thereof and'being adapted tobe seated in the front end of the" projectile, said front cavity havinga concave conical rearward surface, a contact firing member extendingthrough said front cavity and having a shoulder adjacent said conicalsurface, a spring and a spring follower in said front cavity, saidfollower having an annular surface opposite said conical surface andbeing urged theretoward by said spring, a plurality of balls locatedaround said firing memberand betweenthe surfaces, a detonator located insaid rear cavity, the firing pin being adapted topass through an.opening between said'cavities and operating upon lmp-act to lire saiddetonator.

' 3. Fuse for rotative projectiles comprising a body, a primer, devicefor normally preventing contact of said primer and pin, a resilientelement for holding said safety device in safety position,

i for moving said safety f'said resilient Velement said device includinga means operated by centrifugal effect after the beginning of iiightdevice to permit firing,

operating upon said member, and a plurality of balls loa firing pin, anda safety` device when the speed of rotation has dropped to below apredetermined value to return said safety devlce into safety position,the saidl resilient element also serving for holding said firing pin andsaid primer apart after the ing contact between said firing'pin andprimer during transport and movable under centrifugal force into aposition for permitting such firing, a resilient element for holdingsaid safety. device in safety position and formoving it from firingposition to safety position when the centrifugal force has dropped belowa predetermined value, --the said resilient element also serving toforce the firing pin forward in opposition to the effect of airresistance after the safety device has been moved from safety position.

- 5. Fuse for rotative projectiles comprising a body, a primer, a firingpin, safety means including balls adapted to be moved outwardly bycentrifugal force after the pro-v jectile has begun its flight, aresilient element for holding said balls in safety position and forreturning said balls to safety position when the speed of rotationof theprojectile has dropped below a predetermined' value, the said resilientelement also serving for retaining the firing pin and primer apart whenthe safety device is in firing position.

6. A fuse for rotative .projectiles comprising a body, a primer,

ty device including balls for holding said pin from contact with saidprimer while in a normal safety position," means ,on said body forproviding a conical into a firing position after the commencement of theflight of the projectile, and a resilient element for normally holding`said balls in safety position Vduring transport and for re-` turningthem fiom firing position to safety position when the speed of rotationof the,

projectile has dropped to below a predetermined value, the saidresilientelement also servlng for retaining the firing pin and theprimer apart vwhile the balls are in firing seat, and resilient meansVbearing against said ring to hold said balls vin safety position and toreturn the balls fromfiring into safety pos1tion,said resilient meansreacting against a firing pin, and a safe- Y seat for said-balls along`y which they are moved by centrifugal force saidA pin from said firingpinto hold it away from said primer.

8. Fuse for rotative projectiles comprising a body, a primer, a firingpin, a safety means including balls for holding said pin from Contactwith said primer while in a normal safety position, means on said bodyfor providing a conical seat for said balls, a ring for engaging saidballs while on said seat, and a spring engaging' said ring for holdingsaid balls in safety position on said seat and for moving the balls fromfiring to safety position, said spring at its'other end engaging saidfiring pin for holding it away from said primer.-

- 9. Fuse for rotative projectiles comprising a body, a primer, afiringpin, said firing pin including a conical shoulder, means o n saidbody for providing a conical seat having an apex angle less than theapex angle on said conical shoulder, balls located between said shoulderand said seat and actuated by centrifugal force during ili ht to moveaway from the axis of the pro]ectile and thereby force said shoulderaway from said seat, and means for opposing said ,movement of the balls.

10. Fuse for rotative projectiles comprising a body, a primer element, afiring pin element, one of said elements being movable tot ward theother for detonatng the fuse, a safety device for'normally holding themovable element against detonating movement and actuated by centrifugalforce during flight to move from its normal `safety position into ringposition whereby to permit detonating movement of said movable element,a ring member, a flange member on said body, said members being engagedwith the safety device and one of said members having an inclinedsurface whereby the movement of the safety device will cause said ringmember to move axially, and resilient means engaged between said movableelement and said ring member for holding said elements apart and foractuating said ring member for returning said safety device to safetyposition when the rotative speed of the body drops below a predeterminedvalue.

11. A fuse as in claim 10, in which the safety device comprises aplurality of balls, and said one member has a plurality of similarsurfaces for said balls, one of said members also being provided withgrooves spaced at equiangular distances about the fuse axis so that thewalls of the grooves ywill assure a uniform peripheral distribution ofthe said balls. i,

12. Fuse for rotative rojectiles comprisa body, a primer, a ring pin, aprimer holder for said primer, a connection between prising a seat onsaid body for the firing pin and means for raising said firing pin andprimer holder from their position of rest, said means being actuated bycentrifugal force. y

13. Fuse for rotative projectiles comprising a body, a primer mounted insaid body, a ring pin movable in said body, a resilient element adaptedto force said firing pin forwardly in said body away from said primer, aring surrounding said firing pin and engaged by the other end of saidspring so that it is forced rearwardly thereby, ballslocated betweensaid ring and a conical seat on ysaid body and movable between an inwardsafety osition in which they prevent movement of said firing pin and anoutward firing position in which they permit the detonating movement ofsaid firing pin, said ring and seat being constructed and arranged tooppose the outward movement of said balls, said balls in their outwardmovement by centrifugal force upon tiring operating to move said ringforward against said resilient element so that said resilient elementwill cause said ring to return said balls from firing to safety positionwhen the centrifugal force has dropped below a predetermined value.

In testimony whereof, I aiiix my signature.

EDGAR WILLIAM BRANDT.

said firing pin and the primer holder for e normally maintainingthefiring pin away from said primer, said connection yielding l55 under theshock of impact, safety means com-

